Will Viagra or Niagara triumph? Perhaps only Cupid knows who will win a legal tussle in Arkansas, which for once has nothing to do with former President Bill Clinton.

Pfizer, the nation's largest drug manufacturer, has filed a lawsuit against one Lari Williams, who owns a coffee shop in Little Rock. The company has accused Mrs. Williams of misleading the public and sullying the good name of Viagra, a drug used to treat erectile dysfunction in men.

But Mrs. Williams does not peddle pills. Instead, she sells Niagara, a sky-blue herbal drink with pretty bubbles and a romantic kick. Among the good ladies in Arkansas and beyond, Niagara is said to be an aphrodisiac that leaves one all warm and googly eyed for up to four hours.

When she spotted the drink at a beverage trade show in January, Mrs. Williams had the instinctive smarts to realize its potential. She called the Swedish manufacturer and quickly became the nation's sole distributor. In a few weeks' time, orders poured in by the thousands.

"If I can help married people bring romance back into the bedroom, then that's what I want to do," she said last week, fresh from multiple appearances on network TV.

But folks talk.

Why, Niagara sounds like Viagra, and soon, the stores and the TV hosts were calling the drink "Ladies' Viagra," even though the Swedish makers assured one and all that it was named after the waterfalls up Canada's way.

Nevertheless, Pfizer felt threatened by Mrs. Williams and her sound-alike elixir, which is still sold from the backroom of her coffee shop.

Last year, Pfizer sold $1.3 billion worth of Viagra in 90 countries. It can be purchased through hundreds of Internet Web sites and is covered by Medicare and private insurers in 39 states.

The company filed a lawsuit against Mrs. Williams on Tuesday for trademark infringement, among other things.

The lawsuit, heard before U.S. District Judge Stephen M. Reasoner yesterday, seeks a temporary restraining order and a preliminary injunction designed to stop Mrs. Williams from using the Niagara name.

A veteran of several high-profile Whitewater trials three years ago, Judge Reasoner has heard his share of quirky legal complexities. This one promises its share a regular passion play.

Niagara, which contains such herbs as guarana and ginseng, "has no known ability to heighten sexual activity," the lawsuit states, even though it is being called "Viagra for women."

The Viagra trademark, on the other hand, symbolizes a "vast and valuable good," the lawsuit notes. The blue connection the drink is blue, like the pill was an effort on Mrs. Williams' part to "appropriate and benefit from the fame, reputation and good will of the Viagra trademark."

Mrs. Williams is out to "prey upon the expectations of the public for a sexual enhancer, which will inevitably lead to disappointment," the lawsuit states.

But Mrs. Williams, who calls herself "just a little girl from Little Rock," swears by the stuff. She and her husband, Roger, in fact have said Niagara is "unbelievable." They anticipate selling 24 million bottles this year.

A hearing and an eventual trial are expected in the future. For now, Mrs. Williams has no comment, nor does her attorney Marie Bernarde-Miller. Meanwhile, the new Niagara phone ordering system which can handle up to 75 phone calls a minute is humming.

Pfizer, it would seem, has bigger fish to fry.

Three other drug companies are already testing their own versions of erectile-dysfunction drugs that work like Viagra not as an aphrodisiac but by enhancing blood flow to the penis.

In the past year, Viagra has been cited for possible heart and vision-related problems, and for unwanted side effects like headaches. The drug also has surfaced on the recreational drug circuit among club-goers and teen-agers intent on sexual thrills.

Pfizer has been plagued by such imitators as Vaegra and Viagro. "Knock-off" pills like "Erecto" in India and "Wan Ai Ke" in China appear with regularity around the globe, and there are a host of "herbal" Viagras as well.

Viagra "culture" is afoot too and verging upon mythology these days, thanks to advertising and the media.

Playboy tycoon Hugh Hefner is said to keep a "bowl" of Viagra on his nightstand, according to Vanity Fair magazine, and Pfizer itself marketed a "Valentine's edition" of the pill last year.

One company, however, wants to take up where Viagra left off.

Kiotech, a London biotechnology firm, is marketing "Xcite," a facial tissue embedded with pheromones that is meant to enhance sex appeal.

"Our studies in nightclubs show that this pheromone combination dabbed across the wrist and neck makes people appear more confident," said spokesman George Dodd. "Users were described as 'friendlier, warmer and more inviting' with a more attractive smile."

He added, "The Viagra pill gets the machinery working, but does nothing to get you interested."